Composite transmission system



July 4, 1933. D QUARLES 1,917,061

COMPOSITE TRANSMISSION SYSTEM Filed March 50, 1929 3 Sheets-Sheet l F/s. F/G. 53

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6' I63. i 2 4! L //v VENTOE Q A. QUA RLES July 4, 1933.

' D. A. QUARLES COMPOSITE TRANSMISSION SYSTEM Filed March 30, 1929 Sheets-Sheet 3 [7. A. QuARLEs BY ATTORNEY DONAL-DA. amazes; on mst swooro,iiEwjnR'sE LABORATORIES, INCOBBQBAEED, or {NEW yons;

. App licatio ii fired iti i cin so, 1929.:" Seria1" 1 fo.851 353."

QThe pr'esent invention relates to a corn t posit-e transm ssionsystem adapted particulariy toniultinlcx carrier wave transmission; An ohjectlof theinventionis to increase the signal transmission capabilities "of existing systems. This ohject'is lat tained in accord ance :With the inventionhy co npositing. exist ing circuits to provide a number ofladditional circuitsinthe form of carrierchan holswvi-thout di'sti'i'rhin the existin g circni'ts, It is foiind in practice that,[-' in. adding, carrier'channels toanexisting 1i nle5 a point/is I reached at which: the cost of 11' ne" transposi' tion's and other factors in the outside.

construct on} make t tinecononiical to more channelssince; fromvthis point on car rier channels pro vemore costly than" other means cahahle of giving thfif, Same service One of thodifiictdties of using higher and.

higher ffrequencies for carrier transmission arisesfroni thedindnctive effects between Another difticulty neighboring; circuits, v comes from the once sive attenuation-of an Qrc hnary hneat vcryhl'gh frequencies; There isalso considerable 'losshy absorption in. v

' tnrn"condnctor. v v

I cu'it diagraminflsimplified form of 'bothter vrnina'l'sot a-,comp1ete' comp'osited system embodying the'invention; Fig. dis a detailed external structure s' or' cirfcnj ts,: with accompanfving)interference between circuits.

The present invention siirrnonntstoalarge degree these diiiiculties :andi afiords an econo'ni and effectiye 111831154 for increasing the carrying capacity Of' eiistingf'lines. I

recording" tothe invention, a central con ductor' (or i I doctorstransmitting infth'e opposite direce tlon. fiDifierent special arrangements ofthe conductorsare (posihlefhut the preferred wvey rs to surround the s ngle conductor (or group) by" the conductors 'trans nittingin the opposite direction This arrangement, substantially restricts the electromagnetic field to the space comprised within the, outer 'con duotors' The transmi ion efficiency is thiis kept high by reducing he absorption of elec troniagnetic energy i n extrane'ons"structures or circuits Such arrangementQal so inini mizcs the disturhin deflects ofextraneous electromagnetic; fieh'zls ZSOr'ne "or all of the conductors entering into this substantially VQ Q I E. mw' is iom s em/if:- I

connection with both. i v 7 ption contained no the jects of the invention,

conductors) transmitting in one I direct on s (or are) arranged electr cal symmetry "vs lth grespectto a plurality of con; I

c1es comprisinga number- ;of channels.

A ie-memo IIBELL TELEPHONE 151'.- y oortronawiort o1" NEW concentric arrangenicntfmay be used alsofon other transmissions onindividnal circuits or in-xothe'r coinblnations.

line's and "to cables and will be described in panying;drawingsfforni "a part, wil l give a more completeidea of thenature and 1ob aspects? and to such siilosidiary features as -The inventlon 1s applicab l eito. Wire I the compositing circuits, tollv entrance rea I qnirements, c'ahle terminal. constructions} vre- \peaters or repeater j icy-pass constructions,

crossings etc." i a t, In theCdra in'gsf-Figs. land 2; i11ustrate two arrangements which the invention may take when applied to toll line constructions.-

Fig- 34B a diagram offa simplearrangement l' of conductors in accordance wlth thefinven-f tion': to show the eleotrica'l symmetry of the 1 circuit with "respect to a uniform." external or: disturbing fie1d'."Fig. A illustrates-the.

preferred *con struction for i the special re:

Q'Fig. -5 schematic. circomposite network which is showing" of'a' I I suitahle-foruse withthe invention; :'Figs. '7,

j8 j1and 9 illustrate different types "ofl tollljen trance cable connections and Fig. *lO viillus-i trates g'in simplified diagrammatic:fformf a e eolnposited repeatercircuit. Fig.-1'shows a sta dar'dtype of poleand cross-arm construction employed on open Wire] 1ines,' -this construction accommodating 40 hnewir'est v I asdescmhedahove, all ofvthe'sefw 11ne W1res 1 In'accordance With the invention may, by the nse of suitable compositing' nets yworks to he "described later on,; be ,connejcted' v efiectively in parallel as" regards f the "transgniission of a broad band-ofca'rrier "freqnen insulator llon the telephone. pole and the lv ci alconductor indicated atlO in the figure i t fOr these high. fife- 1 both las to its broad conductor is preferably positioned at the center of the space occupied by the 40 line wires.

It will be understood, of course, that the invention is not limited in any sense to the employment of any particular number of line wires nor to the positioning of the re turn conductor at the exact center point of the conductors, however many of the latter areused for transmission of the high frequency carrier Waves. For example, in the case of a toll line carrying 40 wires it is Within the invention to divide these lines int-o groups and to position at or nearthe center of each group a return conductor such as conductor 10 of Fig. 1. In this case conductors of each group are connected in multiple as regards the high frequency carrier waves and form one side of a metallic circuit the opposite side of which is formed by a special conductor such as 10.

Instead of using a single return conductor assumed that all of the 40 line Wires except the Wires 12, 13, 14 and 15 are connected in multiple as regards the high frequency carrier waves and that the central group of conductors 12, 13, 14 and 15 are connected in multiple to form the opposite side of the circuit. These central conductors 1215 may be set aside for use exclusively as the return for the high frequency carrier circuit, but it is preferable merely to select four centrally positioned telephone line Wires for this purpose. Where conductors 12 to 15 are ordinary telephone line Wires, compositing networks to be described later are used in connection with these as in connection with other line Wires to enable the high frequency carrier Waves to be superposed on the circuits without interfering with the use of these conductors for ordinary telephone conversations. As Will appear more fully later on the line Wires may serve for ordinary telephone conversations, or may be connected to provide phantom circuits, or may be composited with carrier channels as individual metallic circuits, or used in any other manner that is customary in the telephone plant.

As in the case of Fig. 1 the total number of conductors may be subdivided into groups each of which comprises a set of conductors for transmitting the high frequency carrier waves in one direction and another set symmetrically positioned with respect to the first set and serving as a return. Where the entire group of conductors on a toll line is used as one composited circuit for the high frequency carrier channels, or for more than one such circuit the group used as the return conductors such as 12 to 15 may comprise a single pair of wires, or a number of pairs of Wires as desired.

The arrangements described in connection with Figs. 1 and 2 comprise a substantially concentric position of the conductors, i. e., the inner conductors are substantially surrounded in space by the outer conductors. While in general this configuration is preferred it is within the invention to arrange the conductors as shown in Fig. 3 where the central return conductor 20 is placed between the conductors,such as 21 and '22 forming the other side of the circuit. The arrows, a, Z), c, etc., in this figure indicate magnetic or electrostatic lines of force extending through the circuit formed by the conductors 20 and 21, 22. Such an external field is without sub stantial effect upon this circuit so long the lines of force extending through each side of the loop are the same. While only three conductors are shown in Fig. 8 the principle illustrated. may, of course, be extended to any number of conductors.

Where a single return conductor such as 10 of Fig. 1 employed it may be desirable to design this conductor to be efficient for the transmission of the high frequencies that are employed by the superposed carrier channels. A suitable construction for this conductor is shown in Fig. l. This construction employs a central core 23 of high tensile strength material surrounded by insulated strands of copper shown at 24. These copper wires or strands are individually insulated order to reduce losses due to the skin effect. This conductor is preferably suspended on low capacity insulators of any suitable type.

The electrical connections for su crposing the composited high frequency channels on the existing line wires are illustrated in a general way in Fig. 5. In this figure the line wires such as are. shown in Figs. 1 and 2 as supported. on poles are indicated at 30. 31

and 82. As will appear more fully hereinafter. these lines may also be included in a cable.) Only three lines are indicated in Fig. 5 but it will be clear from the circuit description how the connections may in practice be extended to any desired number of lines. Between the group of lines 30 to 32 and the special conductor 10 shown at the bottom of the figure there is a derived circuit connection 35 at each terminal of the high frequency composited system. This derived conductor 35 is electrically connected to the lines 30 to 32 by the aid of compositing circuits 86, 37, 38 the nature of which will be described more fully in connection with. Fig. 6. It will be clear from the diagram of Fig. 5 that the line wires 80 to 32 are connected in multiple as regards the derived circuit 35 and that these lines as a group form one side of a composite circuit, the opposite side of which is formed by conductor 10.

The conductor 85 at the left in the figure is shown connected to a group of transmittin and a group of receiving channels which comission of frequencies very much in excess of the practical limit'for present practice. The electromagnetic field set up by the transmitted waves issubstantially confined'to the space bounded-bythe outer conductors. Interference between neighboring lines isthus very greatly reduced and loss by absorption in external circuits or structures is small so that frequencies well in excess of 100 kilocycles per second may be used'for transmitting and receiving in the channels illustrated in Fig. 5, in accordance with this invention.

A type of composite network suitable for use at the points 36, 37, 38 in the system of Fig. 5 is shown in detail in Fig. 6. It is assumed in this figure that the line conductors 30 carry ordinary telephone conversations, metallic circuit or grounded telegraph transmissions and carrier telephone or carrier telegraph channels (or both) employing frequencies up to the order of 30 kilocycles per second. Let it be assumed that the dividing frequencies between the Morse-telegraph signals and the lower limit of the telephone currents is of the order of 150 cycles per second (frequency f while the dividing frequency between'the upper speech limit and the lower limit of the carrier telephone range is of the order of 3200' cycles per second (frequency The shunt portion of the composite network as shown in Fig. 6 comprises coils B (1 2, 3/lseries aiding) and D, and condensers C C and C This structure will be resonant .at the two frequencies f and f and anti-resonant at frequency when given the following design formulae where B is small ascompared with D and C is small as comparedwith C I i (where frequencies are expressed in cycles per second, inductances in henries and capacities in farads). When frequencies and 7% are given the values indicated above, i'. e., the dividing frequencies between the different frequency ranges to be transmitted,

' the bridging effect of the composite set can be made negligibly small at transmission frequencies. Coil A (1 2, 34 series aiding) is a carrier frequency choke coil'to keep the composited carrier frequencies that are transmitted in accordance with the present inven 7 of this condenser being to reduce the transmission loss caused by the composite set for clear that the composite network 36" shown.

in Fig. 6 at the opposite terminal of the line 30 may be constructed similarly to the one that has been shown and described in detail.

Fig. 6 and the description that has been given of it assumes that the opposite side of the composited carrier system is formed by I special conductor 10. In the case where the return is formed by existing line conductors as indicated in Fig. 2 it will be clear that compositing networks are to be used on these lines for enabling the composited carrier channels 'to be superposed on these lines (such as 12, 13,14, 15 of Fig. 2) as a group. The compositing networks for these lines may be identical with that shown in Fig. 6.

As stated above the ultra high frequency carrier channels may be superposed upon lines carried in a cable in the same way that has been described for the case of'open wire lines. One side of the circuit may be formed by all or a part of the usual cable conductors in parallel, and the opposite side of the circuit for the high frequency carrier channels may be formed by a special conductor or by group, of the regular circuits. In either case it is preferable to locate the special conductor, or the second mentioned group of conductors, at or' near the center of the cable. Fig.7 illustrates in simplified fashion one manner of connecting an open wire system in accordance with the invention with the terminal of a cable. It is assumed in this case that the cable is a relatively short toll entrance cable. The open wire lines 30, 31, etc., are individually connected to the corresponding lines in the cable and the special return conductor 10 is connected to a special pair or quad 7 O at the center of the cable; All of the ordinary transmissions carried by the lines 30, 31 such as Morse telegraph, speech currents and carrier currents pass directly into the corresponding individual cable conductors. Also the high frequency composited carrier waves transmitted bythe special conductor 10 and bythe special quad or pair in the cable.

In the case where the centrally positioned return path for the composited carrier channels consists of a group of open wire'conductors instead of the special conductor 10, these conductorswould be connected to corresponding centrally located cable pairs in the samemanner that the lines and 31 of' Fig.7 are connected to the outer pairs of the cable. This type of connection may extend to all of the cable pairs although Fig. 7

illustrates the connections as being;-made'to'., only a few." v f -Whilethetypeof connectionshownfin Fig 7 willsuifice forrelatively shorttoll entrance"- cables: it is preferable 111* the case of some he cable-in Fig. 8 may befthesame' fas"those Where the telephone cable is tool long toj 1 a permit of transmitting the compos,ited;high

described above in the case-of Fig. 7

frequency carrier WaVesthrOug'h- 'ita jtype of I 3O, 31,"etc.1areto be connected-tea long tele phone cable; These lines are providedgwithl composite "networks 36,"=37;:.,etc. of the type: "prei io'u'sly described lfor deriving: a terminal) v p'ointf The deri 5 connection shown in Fig; 9n11ay bet-employed."

Here it: is assumed that -the open wire lines connection 135' for the high "frequency com;

posited channel. Beyond these networks the open'wi'rej lines continue to the cable'jnnction' nectied preferably throughthe primaryoft transformer 7 4' tothespecial return conductor lOwhich-serves as the return fortl 'e'jopenwy re lines 30, 31,etc. as'a'g"roup; cable i's-pari this case the long telephone alleled by a conductor offspecial. construction shown at 7 5. This conductorisfdescribedjand claimed in my copending application; Serial N0.'--351,304, filed' March 30, 192%Patent'NQ? 1,873,477, 'issu'ed August 23,- 1932, to which; a

' nels an-d similar filters 89" and a90"-arejconv-' referencejmay be made-for a, more complete description. It is sufiicientfor present pur i poses to state that the special conductor 75 comprises an outer cylindrical shell76and an inner cylindrical core'77.- These coaxial cy1-1 inders/Zfi and 77 arepreferablyformed-by i braiding metallic strands to form noncjol lapsing, butrela'tively flexible cylinders of high; electrical conductivity, but small capac members some of whichlfare shoWn'at 78fly ity tofeach other. The coaxial alignment of the cylinders is 'obtained by the IISGYOf tension These-may consistof cords :of some "suitable textilernaterial which may behbraided into the structure along with the'metaHicstrands,

These. tension members serye'to suspend the inner conductor from the outerv and at: the": sainetime possess low dielectric capacity s'o that th space between the iconductorsfcon-f tains substantially only air. j

This special. conductor iniij b piaceai lve'd circuit conductorsmefis con? larly econnect'e ilftheirepea-terspacingis'not theisame or} allottheldifierentvkinds'of transmissionstear;' T i ri'ed by'thelines- 30, i3 l,*etc be provided at any point to one-i of ith eitypes I of transmission \and' fa suitable byj-pass cir-j underground f or suspended; on; a telephone toll line to travers'egthesame-distancea's the telephonecablrifthe high frequency composited fcirci1itiis to be carried *to openlwire,

lines at "the Oppo'site' terminal of *the cable.

merely connecting the} secondary i7 9150f the Q ltivansfor nen to .thefconductors '76 and77 re l] 1 the ci1cuit for the 'compositedhigh frequen cy carrier?cha inelsginayfbe by passeduaround" y the repeaters either-{With or without thefine I R clusionof amplifying repeaters in the comf" positedcircuitailn Fig-"10; for' exanipleythe' lineBOi'sslioWnascomprising seCtionsBQ-aIid.

- 80 'betweenwhichfthere is connected a'lusual 22 type telephonelrepeater 80 comprising an" east repeaterSI- and a west'irepea'ter 82." C0 j ugate coil c onnefcfti0ns183iand 84:.a'nd balancmg-networks 85 r'and 86eas ordinarily use areshown.

32 evtc;,fnot'slrown'in-this figure would'con 5 tainlsimila riindividual repeaters. Moreov'en' 'the'sefindiyidllal:lines'might beproyidedwith carrier\.-repeaters or carrier *by pass connections asfdisclosed: morefullyi'in the Espen schiedpatents hereinbefore referred to; 3

Y In order to continue the,comp'ositedcircnit works 3 6 3640f the type previously described,

turn conductor 10 are groupingv-filters89and 'for the high ffrequency ca'rrier channelsx;" i 5 J u iaroundgthe. repeating point;compositing netwe," are connected theyarious indiyidual'tele z' phoneflines in order to iderivetheaconductors 135, for thea'coinposited? carrier Waves, Connected between"conductor l35 an'd the Ire 9Q5fo1 passing theQeastWardI=and westward groups of: frequencies"respectively.that are I a used for the-composit'edl high frequencych an- 'necte'd Ebetween derived conductor '13515ari'd- "special conductor '10,.' An eastward repeater '92 isishbwn connected betweenthe filters-89 and-;89'"*a nd fa westwardrepeater93 is simi- 1 betweenithe-yyestward group repejate i i'mayf cuitor 'circuitsimay'b'ejprQVidd for "the ther stead i i ins i p fl'wsoffoiiatele .Ph urr n si'a n mp i yin ypas iir cuit suchas a repeating ic oilfmayff be" used I presenting ilow impedance between the ":line' sections 3O' a I1d;3(lforthespeech-freopuencies f y but high impedance for the; h

,cfjomposited' carrier "channels,- fhe latter are it then transmitted through the repeaters 92, 93;

It will be understood that in, each instance where a special return conductor has been referred to a group of ordinary line conductors may be employed instead as was described more fully in connection with Fig. 2. In the case where the high frequency coin range of frequencies is transmitted in only one direction.

The various interconnecting, terminating and other special provisions that have been illustrated and described for enabling the high frequency composited channels to be carried by ordinary telephone circuits are, of course, capable of considerable variation as are also the dispositions of the lines, cables, etc. to suit transmission requirements that may be met in practice... All of these specific provisions are to be considered therefore as illustrative rather than as limiting and the invention is to be construed broadly as determined by the scope of the appended claims. 1 I

What is claimed is:

1. A wave transmission system comprising a conductor forming one side of a transmis sion line and a plurality of conductors in parallel forming the return, said latter conductors surrounding said one conductor symmetrically in space and serving also for other circuits.

2. A composite transmission system comprising a plurality of conductors some of which comprise separate transmission circuits for message currents and all but one of'which together make up an array of conductors spaced around said one conductor symmetrically and forming in parallel one side. of another circuit of which said one centrally positioned conductor is the return.

3. In a wave transmission system, conduc tors including pairs, certain pairs of which are connected in multiple to form one side of a composite transmission circuit, the return for which is located. within the space bounded by said certain conductors and symmetrically electrically with respect thereto.

4. In a wave transmission system, conductors paralleling one another and electrically isolated from'one another along their lengths, including pairs, at least one of which con ductors is positioned between pairs of the others and has electrical symmetry relative to them as respects an external interfering field, means for utilizing said one conductor as one side of a composite wave transmission system and means to use said pairs of other conductors in common as the opposite side of said system. l

5. A system in accordancewith claim t in p which said other conductors also serve in pairs as transmission circuits for other kinds of transmission. s

6-. A system in accordance with claim 4 in which said other conductors are metallic tele phone lines for transmitting telephonic messages and are also composited for D. C. telegraph transmission.

7. A system in accordance with claim 4 in which said other conductors are also connected in pairs to serve as individual circuits for multiplex carrier'wave transmission.

8 An open wire line comprising a group I of conductors strung on a pole lead and formor in groups, a special line-conductor cene trally and substantially symmetrically positioned electrically with respect to said group of lines, and means for superposing highfrequency carrier Wave channels on the composite circuit formed by said group of lines, said special. line conductor and said derived conductors.

10. An open wire line comprising a central group and an outer group of conductors carried on .a polesystem, the outer group being located in space on opposite sides of the central group and electrically symmetrically with respect thereto, and means for compositing high-frequency carrier channels on one of said groups of conductors in parallel, the other group of conductors serving in multiple as the return, the conductor comprising each group serving in pairs for the'transmission of other message waves.

11. A signal transmission system compris in g a cable containing a number of pairs of conductors serving astelephone line circuits, and a composite transmission circuit formed by one or more conductors near the center of the cable one side of the circuit and a number of said telephone pairs surrounding said central conductors connected in multiple as the return side of said composite circuit, said composite circuit serving in common for a number of high-frequency carrier Wave channels. 1 V

12. A system as claimed in claim 11 in pa'city of thecomposite system;

which the centrally located portion of the composited system'is spaced fromf-the'sur roundin conductors to'reduce the shunt ca- 13."In a repeater teleph'one'transmissi'on system, means to superpose carrier channels upon a number of telephone line c rcuitsin multiple, means at a repeater station for deriving from the multiple telephone line circuits a circuit in Whichflthe carrierchannelf Waves flow to the exclusion oftelephonejcur rents, and transmission paths at. 'theI-- re-' peater station connectingopposite lines sections with one another and said derived circuit With a similar circuit derived from said opposite line sections iii-multiple, certain of said transmission paths containing amplify; "ing repeaters' Y 14. A system as defined in claim 13 in} whicheach of said derived cir'cuits' is" connected to a pair of directional filters afor sepa-5 rating eastward from westwardcarrier chanads} and an amplifying repeater connecting each pair'of filters, eastward to eastward and I Westwardtowestward.

' 15. A'1on g" toll line connection including open w re lmes and cableyme'ans to transmit carrler Waves over a number ofthe O PGII- WIIGf lines in multiple a,.r eturn for the carrier cuitin whichthe carrier wave's'flow to the ex? GlllSlOl'l of speech Waves, and2a'spec1a1 [lovv{ 1 capacity :coaX1a1conductor -11ne connected-to;

said derived circuit and para-llelling theeable andtraversed by said carrier waves. Q

J In Witness Wher'eoflfI hereunto subscribe V my ,'name" this 29thday of March; 1929.

- i DONALD-A. QUARLESQJ "f giot 

